*{
  margin: 0;
  padding: 0;
  list-style: none;
  box-sizing: border-box;
}
.box{
  width: 100vw;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
header{
  width: 100%;
  height: 40px;
  background: deepskyblue;
  border-bottom: 1px solid rgb(255, 255, 255);
  display: flex;
  justify-content: space-between;
  padding: 0 12px;
  align-items: center;
  color: #fff;
}
footer{
  width: 100%;
  height: 45px;
  background: #f5f5f5;
  border-top: 2px solid #ccc;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 20px;
  span.act{
    color: deepskyblue;
  }
}
main{
  flex: 1;
  overflow-y: scroll;
}